Performance-based and patient-reported outcome measures for custom ankle-foot orthosis users: reliability, validity, and sensitivity evidence.

Abstract

To evaluate the psychometric properties of performance and patient-reported outcome measures (PROMs) for custom ankle-foot orthosis (AFOs) users. Current AFO users completed two assessments one week apart; new AFO users completed an assessment before device delivery and at one- and two-months post-delivery. Seventy current and 31 new users consented and provided data. We found evidence of minimal floor and ceiling effects for most PROMs; the exceptions were measures of service satisfaction. The Orthotics and Prosthetics Users' Survey (OPUS) Lower Extremity Functional Status (LEFS) measure demonstrated excellent test-retest reliability; the 5-level EuroQol (EQ-5D-5L), OPUS Health-Related Quality of Life, Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST 2.0), and PROMIS Physical Function measures demonstrated good reliability. Evidence of known-groups validity is provided by associations between obesity and walking speed. PROMs measuring physical function (LEFS, Rivermead Mobility Index (RMI), PROMIS Physical Function) correlated at least moderately with performance instruments. We observed moderate to large correlations between PROM and performance instrument changes for the EQ-5D-5L, LEFS, RMI, and PROMIS Physical Function. Results provide evidence of test-retest reliability, construct validity, and sensitivity to change for some PROMs. PROMs and performance instruments provide overlapping but complementary evidence regarding the benefits of custom AFOs.